Electricmagnetism 5/15/15

Major Topics of the Final  Work and Power  Conservation of Energy  Waves  Sound  Light Reflection and Refraction  Electromagnetic Waves  (Electromagnetic Induction)  ~40%  ~10%

True or False 1. When a battery no longer works, it is out of charge. 2. A battery can be a source of charge in a circuit. The charge which flows through the circuit originates in the battery. 3. Charge becomes used up as it flows through a circuit. The amount of charge which exits a light bulb is less than the amount which enters the light bulb.

True or False 4.When current runs through a wire a magnetic field is produced. 5.Magnetism is produced by moving charges 6.The force of electromagnetism is stronger then the force of gravity. 7.Electromagnetism can exert of force on an object without touching it.

True or False 8. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped. 9. The local electrical utility company supplies millions and millions of electrons to our homes everyday. 10. High voltage circuit means there is a large current.

Conditions for a Circuit  There must be a closed conducting path that extends from the positive terminal to the negative terminal.  There must be an electric potential difference across the two ends of the circuit.

Battery and Circuits  A negative charge has the least amount potential energy at positive terminal  A negative charge has the greatest amount potential energy at negative terminal Voltage = Potential Difference High PE Low PE

Waterslide vs. Circuit

Voltage Sources (batteries)  Do work on each charge it encounters  Which transfers into electric potential energy

A “Dead” Cell Phone When your cell phone “dies”:  It no longer has the energy to power it  It still has plenty of charge (electrons), just not the ability to do work on the charges

Electromagnetism  Electromagnetism: the interaction of electric currents or fields and magnetic fields.  Electric current and moving charge is the source of ALL magnetism

Voltage Sources Examples  Ex 1) Low voltage and low current  D-Cell battery: 1.5 V and 0.1 A  Low waterfall with only trickle of water flowing

Voltage Sources Examples  Ex 2) High voltage and high current  Power lines: 50,000 volts and 65 A  High waterfall with a river of water flowing over it

Voltage Sources Examples  Ex 3) High voltage and low current:  Electric fence: 6000 V and 0.1 A  High waterfall with only trickle of water flowing

Voltage Sources Examples  Ex 4) Low voltage and high current:  Car battery: 12 V and 30 A  Low waterfall with a gushing river of water flowing

True or False Revisited 1. When a battery no longer works, it is out of charge. 2. A battery can be a source of charge in a circuit. The charge which flows through the circuit originates in the battery. 3. Charge becomes used up as it flows through a circuit. The amount of charge which exits a light bulb is less than the amount which enters the light bulb.

True or False 4.When current runs through a wire a magnetic field is produced. 5.Magnetism is produces by moving charges 6.The force of electromagnetism is stronger then the force of gravity. 7.Electromagnetism can exert of force on an object without touching it.

True or False Revisited 8. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped. 9. The local electrical utility company supplies millions and millions of electrons to our homes everyday. 10. High voltage circuit means there is a large current.

Next Week  Mon. 5/18/15 – Open note quiz with handwritten notes only!  Wed. 5/19/15 – Review is due, everyone need to complete the review  Thurs. 5/20/15 – Review for the final  Fri. 5/21/15 – Final Exam can use one page (1 sided) of formulas and notes